Apache
/
activemq
mirror of https://github.com/apache/activemq.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Patch for AMQ-606 to allow slow consumers to have their old messages discarded. For background to the issue see http://docs.codehaus.org/display/ACTIVEMQ/Slow+Consumers 

Provides a way to set a limit on the pending messages to be dispatched to a subscription so that if that limit is reached, old messages are discarded. This will avoid the non-durable topics from getting blocked due to slow consumers


git-svn-id: https://svn.apache.org/repos/asf/incubator/activemq/trunk@382459 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
James Strachan 2006-03-02 17:56:21 +00:00
parent 4a65a33af0
commit 95d0dec008
7 changed files with 204 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
activemq-core/src/main/java/org/apache/activemq/broker/region/AbstractSubscription.java
View File

@ -115,4 +115,16 @@ abstract public class AbstractSubscription implements Subscription {
public boolean isSlaveBroker(){
return broker.isSlaveBroker();
}
public ConnectionContext getContext() {
return context;
}
public ConsumerInfo getInfo() {
return info;
}
public BooleanExpression getSelector() {
return selector;
}
}

12
activemq-core/src/main/java/org/apache/activemq/broker/region/TopicRegion.java
View File

@ -204,7 +204,17 @@ public class TopicRegion extends AbstractRegion {
return sub;
}
else {
return new TopicSubscription(broker,context, info, memoryManager);
TopicSubscription answer = new TopicSubscription(broker,context, info, memoryManager);
// lets configure the subscription depending on the destination
ActiveMQDestination destination = info.getDestination();
if (destination != null && policyMap != null) {
PolicyEntry entry = policyMap.getEntryFor(destination);
if (entry != null) {
entry.configure(answer);
}
}
return answer;
}
}

22
activemq-core/src/main/java/org/apache/activemq/broker/region/TopicSubscription.java
View File

@ -42,7 +42,7 @@ public class TopicSubscription extends AbstractSubscription {
final protected UsageManager usageManager;
protected int dispatched=0;
protected int delivered=0;
private int maximumPendingMessages = 0;
private int maximumPendingMessages = -1;
public TopicSubscription(Broker broker,ConnectionContext context, ConsumerInfo info, UsageManager usageManager) throws InvalidSelectorException {
super(broker,context, info);
@ -56,15 +56,17 @@ public class TopicSubscription extends AbstractSubscription {
// have not been dispatched (i.e. we allow the prefetch buffer to be filled)
dispatch(node);
} else {
synchronized (matched) {
matched.addLast(node);
// NOTE - be careful about the slaveBroker!
if (maximumPendingMessages > 0) {
// lets discard old messages as we are a slow consumer
while (matched.size() > maximumPendingMessages) {
MessageReference oldMessage = (MessageReference) matched.removeFirst();
oldMessage.decrementReferenceCount();
if (maximumPendingMessages != 0) {
synchronized (matched) {
matched.addLast(node);
// NOTE - be careful about the slaveBroker!
if (maximumPendingMessages > 0) {
// lets discard old messages as we are a slow consumer
while (matched.size() > maximumPendingMessages) {
MessageReference oldMessage = (MessageReference) matched.removeFirst();
oldMessage.decrementReferenceCount();
}
}
}
}

43
activemq-core/src/main/java/org/apache/activemq/broker/region/policy/ConstantPendingMessageLimitStrategy.java Normal file
View File

@ -0,0 +1,43 @@
/**
*
* Copyright 2005-2006 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.broker.region.policy;
import org.apache.activemq.broker.region.TopicSubscription;
/**
* This PendingMessageLimitStrategy is configured to a constant value for all subscriptions.
*
* @org.apache.xbean.XBean
*
* @version $Revision$
*/
public class ConstantPendingMessageLimitStrategy implements PendingMessageLimitStrategy {
private int limit = -1;
public int getMaximumPendingMessageLimit(TopicSubscription subscription) {
return limit;
}
public int getLimit() {
return limit;
}
public void setLimit(int limit) {
this.limit = limit;
}
}

41
activemq-core/src/main/java/org/apache/activemq/broker/region/policy/PendingMessageLimitStrategy.java Normal file
View File

@ -0,0 +1,41 @@
/**
*
* Copyright 2005-2006 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.broker.region.policy;
import org.apache.activemq.broker.region.TopicSubscription;
/**
* A pluggable strategy to calculate the maximum number of messages that are allowed to be pending on
* consumers (in addition to their prefetch sizes).
*
* Once the limit is reached, non-durable topics can then start discarding old messages.
* This allows us to keep dispatching messages to slow consumers while not blocking fast consumers
* and discarding the messages oldest first.
*
* @version $Revision$
*/
public interface PendingMessageLimitStrategy {
/**
* Calculate the maximum number of pending messages (in excess of the prefetch size)
* for the given subscription
*
* @return the maximum or -1 if there is no maximum
*/
int getMaximumPendingMessageLimit(TopicSubscription subscription);
}

42
activemq-core/src/main/java/org/apache/activemq/broker/region/policy/PolicyEntry.java
View File

@ -18,6 +18,7 @@ package org.apache.activemq.broker.region.policy;
import org.apache.activemq.broker.region.Queue;
import org.apache.activemq.broker.region.Topic;
import org.apache.activemq.broker.region.TopicSubscription;
import org.apache.activemq.filter.DestinationMapEntry;
/**
@ -35,6 +36,7 @@ public class PolicyEntry extends DestinationMapEntry {
private boolean sendAdvisoryIfNoConsumers;
private DeadLetterStrategy deadLetterStrategy;
private int messageGroupHashBucketCount = 1024;
private PendingMessageLimitStrategy pendingMessageLimitStrategy;
public void configure(Queue queue) {
if (dispatchPolicy != null) {
@ -59,6 +61,15 @@ public class PolicyEntry extends DestinationMapEntry {
topic.setSendAdvisoryIfNoConsumers(sendAdvisoryIfNoConsumers);
}
public void configure(TopicSubscription subscription) {
if (pendingMessageLimitStrategy != null) {
int value = pendingMessageLimitStrategy.getMaximumPendingMessageLimit(subscription);
if (value >= 0) {
subscription.setMaximumPendingMessages(value);
}
}
}
// Properties
// -------------------------------------------------------------------------
public DispatchPolicy getDispatchPolicy() {
@ -94,7 +105,8 @@ public class PolicyEntry extends DestinationMapEntry {
}
/**
* Sets the policy used to determine which dead letter queue destination should be used
* Sets the policy used to determine which dead letter queue destination
* should be used
*/
public void setDeadLetterStrategy(DeadLetterStrategy deadLetterStrategy) {
this.deadLetterStrategy = deadLetterStrategy;
@ -105,14 +117,30 @@ public class PolicyEntry extends DestinationMapEntry {
}
/**
* Sets the number of hash buckets to use for the message group functionality.
* This is only applicable to using message groups to parallelize processing of a queue
* while preserving order across an individual JMSXGroupID header value.
* This value sets the number of hash buckets that will be used (i.e. the maximum possible concurrency).
* Sets the number of hash buckets to use for the message group
* functionality. This is only applicable to using message groups to
* parallelize processing of a queue while preserving order across an
* individual JMSXGroupID header value. This value sets the number of hash
* buckets that will be used (i.e. the maximum possible concurrency).
*/
public void setMessageGroupHashBucketCount(int messageGroupHashBucketCount) {
this.messageGroupHashBucketCount = messageGroupHashBucketCount;
}
public PendingMessageLimitStrategy getPendingMessageLimitStrategy() {
return pendingMessageLimitStrategy;
}
/**
* Sets the strategy to calculate the maximum number of messages that are
* allowed to be pending on consumers (in addition to their prefetch sizes).
*
* Once the limit is reached, non-durable topics can then start discarding
* old messages. This allows us to keep dispatching messages to slow
* consumers while not blocking fast consumers and discarding the messages
* oldest first.
*/
public void setPendingMessageLimitStrategy(PendingMessageLimitStrategy pendingMessageLimitStrategy) {
this.pendingMessageLimitStrategy = pendingMessageLimitStrategy;
}
}

50
activemq-core/src/main/java/org/apache/activemq/broker/region/policy/PrefetchRatePendingMessageLimitStrategy.java Normal file
View File

@ -0,0 +1,50 @@
/**
*
* Copyright 2005-2006 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.broker.region.policy;
import org.apache.activemq.broker.region.TopicSubscription;
/**
* This PendingMessageLimitStrategy sets the maximum pending message limit value to be
* a multiplier of the prefetch limit of the subscription.
*
* @org.apache.xbean.XBean
*
* @version $Revision$
*/
public class PrefetchRatePendingMessageLimitStrategy implements PendingMessageLimitStrategy {
private double multiplier = 0.5;
public int getMaximumPendingMessageLimit(TopicSubscription subscription) {
int prefetchSize = subscription.getConsumerInfo().getPrefetchSize();
return (int) (prefetchSize * multiplier);
}
public double getMultiplier() {
return multiplier;
}
/**
* Sets the multiplier of the prefetch size which will be used to define the maximum number of pending
* messages for non-durable topics before messages are discarded.
*/
public void setMultiplier(double rate) {
this.multiplier = rate;
}
}